During the normal course of steam generator operation, it may be necessary to quantitatively measure the degree of stress and strain experienced by various steam generator tubes disposed within the generator. However, due to the nature of steam generator construction, the external surfaces of these tubes are frequently inaccessible. As a consequence, techniques have been developed to bond strain gages to the inner surface of the tubes. Unfortunately, these techniques are generally unsatisfactory. Moreover, many of the gages are unsuitable for installation within the generator; they are incapable of withstanding the severe service conditions encountered within the tubes.
There is, however, a commercially available strain gage ideally suited for steam generator tube installation. This gage may be attached to a tube by known capacitive discharge spot welding techniques. Unfortunately, the tooling presently available for such an operation is both hand held and hand operated. Furthermore, the tooling required is too bulky for use in confined spaces. Other attachment techniques require access to both ends of the tube, as well as access to the inner and outer diameters of the tube at the exact point of strain gage placement.
Clearly, an improved apparatus for attaching a strain gage to the internal surface of a steam generator tube is necessary and desirable.